The biocide and disinfecting properties of oxidising solutions containing active chlorine under various forms are known in various technical fields. Diluted hypochlorite solutions are used, for instance, in food disinfection and for sterilising tools employed in food processing, hotels and sanitary applications. The use of active chlorine-containing solutions in agricultural applications such as the preventive or therapeutic treatment of microorganism-induced pathologies, on the other hand, is not of common practice, due to the poor efficacy displayed by commercially available products of this kind, that in most of the cases present remarkable drawbacks. In particular, the complex dissociation and disproportioning equilibria whereto chlorine-containing active species are subject, require the use of stabilisers to preserve the nominal composition. For example, the common sodium hypochlorite solutions are stabilised with alkalis, in the simplest case with caustic soda (up to pH 11-12) or with buffered basic solutions (such as sodium tetraborate solutions), in any case at pH not lower than 9.5. Excessively basic solutions are not fit for the direct utilisation in agricultural applications, and also excessive amounts of sodium can pose some problems, as known to those skilled in the art; in particular, biocide solutions fit for sprinkling vegetal species should have a pH not higher than 9, and preferably comprised between 6 and 8.
A very effective source of active chlorine in this pH range is hypochlorous acid, whose biocide properties are known in the art, and which presents the further advantages, compared to commonly employed disinfectants, of being extremely cheap and of releasing no toxic or noxious residues. The use of hypochlorous acid is, nevertheless, hindered by practical reasons, mainly associated with its limited stability which reduces the allowed storage time below levels of practical utility. Moreover, concentrations suitable for an effective use without harmful side-effects for the cultivations (0.01 to 2 g/l) would imply either the packaging and handling of an extremely diluted product, entailing the use of excessive volumes, or the need of diluting the product each time, an operation which, besides being impractical, is also questionable due to the risk of accidentally contaminating the product with substances, for instance metals, that could further reduce its already limited stability.
For this reason, the biocide treatments for the prevention and cure of pathologies induced by microorganisms such as fungi and bacteria are currently carried out by means of a great variety of chemical agents which release toxic residues to the environment and have an often considerable cost.
It would, therefore, be desirable to provide an inexpensive and effective source of active chlorine for biocide treatments in agricultural applications, suitable, for example, in preventive or therapeutic treatment of vegetable pathologies induced by microorganisms such as fungi or bacteria.